The invention relates to a snowboard binding comprising a base plate having two at least approximately parallel lateral sides and bearing:                an arch extending obliquely rearward,        a rear support piece rising inside the arch and displaceable on the base plate in parallel with the lateral sides of the base plate, and        a foot strap for passing over the boot in the region of the foot and displaceable on the base plate in parallel with the lateral sides of the base plate,        and kinematic linking means between the foot strap and the rear support piece.        
The word “strap” must in this case be understood in its widest sense. In particular, it comprises strips made from plastic material in one or two parts and their adjustable means of attachment or of coupling.
This type of binding is generally called a strap binding, as opposed to automatic step-in bindings in which the sole of the boot has to include a rigid piece interacting with a binding mechanism.
The binding in question may be equipped with two straps, a first strap for passing over the boot in the region of the instep, and a second strap for passing over the front part of the foot, or a wider, single strap extending over the foot and over the instep.
Strap bindings are generally designed so that they can be adjusted to the user's boot size. The simplest solution consists in fixing the rear support piece, or rear arch bearing the support piece, and the foot strap on two parallel vertical walls of the base plate which have a row of holes in which the rear support piece, or the arch, and the front foot strap can be positioned selectively and fixed in the holes by means of screws and nuts. A construction of this type is described in documents U.S. Pat. No. 5,609,347, the content of which is incorporated by reference, and U.S. Pat. No. 5,727,797, the content of which is incorporated by reference. In the case of an arch fixed on the base plate, it has been proposed in document U.S. Pat. No. 5,261,689, the content of which is incorporated by reference to replace the holes for positioning the rear support piece with an aperture with a notched periphery, a fixing member being fixed in the notched part.
Document U.S. Pat. No. 6,283,482, the content of which is incorporated by reference describes a strap binding in which the rear support piece is fixed in a similar manner to that described in document U.S. Pat. No. 5,261,689, the content of which is incorporated by reference, the fixing member including a notched small plate that can be tightened and loosened using a cam lever, allowing rapid adjustment of the position of the rear support piece. The foot strap is not, however, adjustable, so that during an adjustment the position of the boot on the snowboard varies, which is undesirable in principle, the behavior of the snowboard being affected thereby.
The fixing of the rear support piece and of the foot strap on the base plate by means of screws requires at least four screws and often six screws, as is the case of the binding according to U.S. Pat. No. 5,727,797. For snowboard rental outlets, which very often have to adjust the bindings, this therefore requires the screwing in and unscrewing of at least four nuts or screws, with the risk of losing nuts and screws, without taking into account the time spent on such an operation in order to obtain symmetrical adjustment which does not modify the position of the boot relative to the snowboard.
In order to offset this drawback, a snowboard binding with symmetrical adjustment based on an axial screw having two opposed screw threads, ensuring the displacement of nuts linked respectively to a rear support piece and to one or two front support pieces, was proposed in document U.S. Pat. No. 6,267,403, the content of which is incorporated by reference. This construction occupies a relatively significant height above the base plate, given that the screw and the nuts, located above the base plate, have themselves to be covered over with a covering plate.
The binding described in document FR 2 732 611, the content of which is incorporated by reference, also describes a snowboard binding in which the length can be adjusted by means of an axial screw, the position of the rear binding element, however, being fixed, such that adjustment is not symmetrical.